Soluble Catalysts for Copper Recovery from Low Grade Primary Copper Sulfide Ores

世界上大约80%的铜来自硫化铜矿CuFeS2。通常，黄铜矿矿石经过浓缩，然后进行冶炼，以获得高纯度铜。然而，这些原生铜矿的品位一直在稳步下降，这使得这条路线对今天的许多低品位矿石来说并不经济。处理低品位铜矿的一种潜在的低成本替代方案是堆浸。然而，众所周知，由于矿物钝化，黄铜矿很难浸出，到目前为止，堆浸的商业应用仅限于次生硫化铜(辉铜矿，Cu2S)矿石。多年来，低品位黄铜矿的堆浸(与溶剂萃取和电积相结合)一直是湿法冶金的“圣杯”，有几种方法显示出了一些前景，包括在热堆中使用极端嗜热微生物，其中黄铁矿首先被氧化产生热量，以及使用氯化物作为催化剂。然而，热堆不可靠，难以控制，而且氯化物具有极强的腐蚀性。 UBC最近的工作表明，可以用某些可溶物种催化黄铜矿的浸出。对黄铜矿电极的电化学测试表明，少量的专有(虽然便宜且容易获得)可溶性有机化合物(将被称为MFD)使电极去钝化。柱浸和水槽浸出试验的初步结果表明，MFD是一种有效的铁浸出催化剂。加入MFD可明显防止钝化，提高浸出率。此外，加入MFD后，停止浸出的一柱矿石又开始快速浸出。 这些结果是非常有希望的。如果MFD可以在堆浸条件下使黄铜矿去钝化，那么这将使黄铜矿与辉铜矿一样容易堆浸。这将是一个重大突破，将从根本上改变铜矿开采的经济性。 拟议的研究将集中于开发一种可行的使用MFD的黄铜矿堆浸工艺。具体目标包括： 1用MFD进行柱浸实验，确定最佳工艺条件 2培养铁和硫氧化细菌，使其对MFD的抗性达到所要求的水平 3改进测定浸出液中MFD浓度的分析方法 4确定MFD(如果有)对铜SXEW的影响 5测定MFD催化浸出反应动力学 6利用MFD建立了堆浸过程的综合数学模型。 开发黄铜矿和黄铜矿精矿搅拌槽生物浸出的并行技术 8确定MFD催化作用的基本机理 9测试与MFD具有相同官能团的替代有机化合物 10测试其他重要硫化物矿物的MFD

Roughly 80% of the world’s copper comes from the copper sulfide mineral chalcopyrite, CuFeS2. Typically, chalcopyrite ores are concentrated and subsequently smelted to obtain high purity copper. However, the grades of these primary copper ores have been steadily decreasing, which renders this route less than economical for many of today’s low-grade ores. A potential low-cost alternative to process low-grade copper ores is heap bioleaching. However, chalcopyrite is notoriously difficult to leach due to mineral passivation, and commercial application of heap bioleaching has thus far been limited to secondary copper sulfide (chalcocite, Cu2S) ores. Heap bioleaching of low-grade chalcopyrite ores (combined with solvent extraction and electrowinning, or SXEW) has been the “holy grail” of hydrometallurgy for many years, and several methods have shown some promise, including the use of extreme thermophilic microbes in hot heaps where pyrite is first oxidized to generate heat, and the use of chloride as a catalyst. However, hot heaps are unreliable and difficult to control, and chloride is extremely corrosive. Recent work at UBC suggests that it is possible to catalyse the leaching of chalcopyrite with certain soluble species. Electrochemical tests on a chalcopyrite electrode showed that small amounts of a proprietary (albeit inexpensive and readily available) soluble organic compound (which will be referred to as MFD) depassivated the electrode. Preliminary results from column and tank leaching experiments show that MFD is a powerful catalyst in ferric leaching. Adding MFD prevented passivation and enhanced the leaching rate significantly. Also, a column of ore which had stopped leaching began to leach rapidly again upon addition of MFD. These results are very promising. If MFD can depassivate chalcopyrite under heap leaching conditions, then this could render chalcopyrite ores as easy to heap leach as chalcocite ores. This would be a major breakthrough which fundamentally alters the economics of copper mining. The proposed research will focus on developing a viable heap bioleaching process for chalcopyrite ores using MFD. Specific objectives include: 1 Conduct column bioleaching experiments with MFD to determine optimum process conditions 2 Culture iron and sulfur oxidizing bacteria to be resistant to MFD at the levels required 3 Refine analytical methods for measuring MFD concentrations in leach solutions 4 Determine the impact of MFD (if any) on copper SXEW 5 Measure the reaction kinetics of MFD-catalyzed leaching 6 Develop a comprehensive mathematical model of heap bioleaching with MFD 7 Develop a parallel technology for stirred tank bioleaching of chalcopyrite ores and concentrates 8 Determine the fundamental mechanism of the catalytic effect of MFD 9 Test alternative organic compounds which share the same functional groups as MFD 10 Test MFD on other important sulfide minerals